A label printer generally prints labels while conveying label paper, which has labels adhesively affixed at a constant interval on a long web, passed the printing position, then peels the labels from the web by means of a peeler mechanism, and dispenses the printed peeled labels from a label dispensing slot. The peeler conveys the label paper around a bend of more than 90 degrees, and uses the stiffness of the label (the rigidity of the label paper) to peel each label from the web. Patent Reference 1 noted below teaches a printer having this type of peeler mechanism.
In this type of label printer the labels are conveyed to the label dispensing slot as the labels are peeled from the web by the peeler, and the web from which the labels have been peeled is discharged through a different path than the labels. Conveying the labels and web stops at the point where only a part of the trailing end of the label in the transportation direction remains affixed to the web. This is because the label will fall out if the printed label is completely separated from the web. Most of the label peeled from the web is exposed externally to the label dispensing slot at this point so that the operator can remove the label. At some point thereafter, the operator removes the printed label.
If the operator does not remove the printed label and the next label is printed and discharged while a label remains in the label dispensing slot, labels with the adhesive face exposed will build up one after another at the label dispensing slot, eventually leading to a paper jam. To avoid this, a reflective optical sensor is generally disposed as a label detector near the label dispensing slot to detect if the printed label remains in the label dispensing slot (that is, to detect the presence of a label). If the label detector detects that the label was removed (detects that a label is not present), the next label printing operation starts.
[Patent Reference 1] Japanese Patent No. 2992363